| * As a rule of thumb, oil should not be expected at subsurface temperatures > [[temperature::150°C]] or a maturation level much above 1.3% R<sub>o</sub>. Dry gas accumulations can occur at shallower depths, but oil is not likely at greater depths. | | * As a rule of thumb, oil should not be expected at subsurface temperatures > [[temperature::150°C]] or a maturation level much above 1.3% R<sub>o</sub>. Dry gas accumulations can occur at shallower depths, but oil is not likely at greater depths. |
− | * Gasification of oil in reservoirs is associated with the formation of pyrobitumen (<ref name=ch11r34>Tissot, B., P., Welte, D., H., 1984, Petroleum Formation and Occurrence, 2 ed.: New York, Springer-Verlag, 699 p.</ref> p. 460–461). | + | * Gasification of oil in reservoirs is associated with the formation of pyrobitumen.<ref name=ch11r34>Tissot, B., P., Welte, D., H., 1984, Petroleum Formation and Occurrence, 2 ed.: New York, Springer-Verlag, 699 p. 460–461</ref> |
| * Absence of an oil leg in the trap prior to charging by gas is indicated by the absence of oil stain with heavy molecular components. | | * Absence of an oil leg in the trap prior to charging by gas is indicated by the absence of oil stain with heavy molecular components. |